There is a paradox that lies in the very heart of human existence. It must be apprehended before any lasting happiness is possible in the soul of a man. The paradox is this: man’s nature, by itself, can do little or nothing to settle his most important problems. If we allow nothing but our natures, our own philosophies, our own level of ethics, we will end up in hell.

This would be a depressing thought, if it were not purely abstract. Because in the concrete order of things God gave man a nature that was ordered to a supernatural life. He created man with a soul that was made to bring itself to perfection in its own order, but to be perfected by Him in an order infinitely beyond the reach of human powers. We were never destined to lead purely natural lives, and therefore we were never destined in God’s plan for a purely natural beatitude. Our nature, which is a free gift of God, was given to us to be perfected and enhanced by another free gift that is not due it.

This free gift is “sanctifying grace.” It perfects our nature with a gift of life, an intellection, a love, a mode of existence infinitely above its own level. — Thomas Merton, Seven Storey Mountain